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Making the most of IPM in Malawi

Over 900 species of insect have been reported to feed on coffee. Although relatively few create significant damage, and few are sufficiently widespread to cause major losses, the white stemborer, Monochamus leuconotus [WSB], has become particularly hard to control since the withdrawal of dieldrin and aldrin as environmental contaminants. However, a highly targeted way of applying insecticide with minimal non-target effects is by the application of insecticide to the stem of coffee bushes. For this reason, a project in Malawi is helping smallholders to test two alternative compounds applied as stem paints for the control of WSB, the main pest ranked by farmers as a major production constraint.

White stemborer, Adult beetle
credit: Rory Hillocks, NRI

However, the main aim of the project is not to provide alternative insecticides but to develop and promote IPM within an Integrated Crop Management (ICM) programme. Control of the main diseases to affect coffee in northern Malawi, Coffee Berry Disease [CBD] (Colletotrichum kahawae) and Coffee Leaf Rust [CLR] (Hemileia vastatrix), are also being addressed by the project. Both fungal diseases have previously been treated by application of copper sprays but the compounds are expensive and often ineffective during the rainy season. Although consideration has been given to the use of granular, soil-applied fungicides as an alternative, these are more expensive than copper compounds and it is felt that regular pruning of coffee bushes and shade trees and some application of fertilizer will, in most cases, provide sufficient control.

Coffee yields obtained by smallholders in Malawi are among the lowest in the world. In contrast, the estate sector in Malawi achieves among the highest yields in Africa. In recent years, the establishment of the Smallholder Coffee Farmers Trust, which has elected farmer representation making it more responsive to farmers' needs, has led to the reformation of the smallholder sector and producer prices have been raised. In addition, the SCFT has agreed to pay the farmers at least 60% of the export price for their coffee. While this does not protect coffee growers from falling world prices, farmers believe they are now receiving a fairer deal, which has resulted in many farmers rehabilitating neglected bushes and expanding the area of coffee grown.

Although the smallholder sector in Malawi is small, representing only 5% of national production, arabica coffee represents the fourth largest export crop. It remains an essential source of cash income and the sector has the potential to support nearly 10,000 households. Whilst this is still a relatively small proportion of people within the country, smallholder coffee is generally of superior quality, which should allow Malawian smallholders to benefit from price premiums. There is now an opportunity through the ICM project to ensure that best practice is encouraged and that the potential increases in coffee production are sustainable.

Coffee Leaf Rust, showing rust pustules
credit: Rory Hillocks, NRI

In Malawi, coffee is grown on steep slopes with the constant threat of erosion, especially when bushes die due to stem borer damage or old age and the soil surface is exposed. The aim of good ICM practice in coffee is thus to prevent erosion and to maintain or increase soil fertility and organic matter content. Mulches and green manure cover crops help to protect the soil from erosion, especially when coffee plantations are being established, and they also help to suppress weeds and return organic matter to the soil. Although mulching can be labour intensive, many coffee growers use banana plants for shade. These need to be regularly thinned to prevent overshading and increased incidence of disease, and the pruned leaves provide readily available mulch.

Although the use of off-farm inputs is discouraged in ICM, it is recognised that pesticides may sometimes be required. Rational pesticide use requires the adoption of at least a simple form of scouting and use of a threshold level of pest numbers in order for spraying to give an economic return. Correct pruning and avoidance of heavy shade can also provide some control of the main diseases e.g. CBD and some of the pests, such as Antestia bugs (Antestisopsis spp.), which is a common pest of arabica coffee throughout sub-Saharan Africa. Encouraging farmers to tolerate some pest damage and to maintain populations of natural enemies of crop insect pests helps to prevent increased pest problems in the future. It may also be more advantageous for smallholders to completely avoid the use of pesticides if they can sell the coffee at a higher premium, on the basis that the coffee is organically grown.

For further information contact Rory Hillocks, NRI

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